1. Field of the Invention
The subject invention generally relates to a window assembly for a vehicle. More specifically, the subject invention relates to a window assembly having a transparent layer with an antenna element disposed within and surrounded by an outer region of the window assembly.
2. Description of the Related Art
Recently, there is an increasing demand in vehicle windshields having clear films or coatings embedded within the windshield for various purposes. Such clear films or coatings often have metal compounds, such as metal oxides, for making the clear films or coatings electrically conductive. These clear films or coatings have been utilized in defogging or defrosting systems and even as active antenna elements for vehicles. More recently, the clear films or coatings have been applied to windshields to absorb heat from sunlight penetrating the windshield. In particular, the clear films or coatings absorb infrared radiation from sunlight. In so doing, the clear films or coatings reduce the amount of infrared radiation entering an interior of the vehicle. The clear films or coatings enable a lower interior temperature as compared to a vehicle having a windshield with no clear films or coatings. As a result, during the warm months, less energy is required to lower the interior temperature of the vehicle. To maximize efficiency of the clear films or coatings to absorb infrared radiation, the clear films or coatings are often applied over a substantial part of the windshield, often covering the entire field of view of the driver.
Traditionally, antennas have been employed on vehicle windshields for a variety of applications. The antennas are often placed upon various locations of the windshield and are energized by a feeder line which is coupled to the antenna. Frequently, it is necessary for the antennas to be disposed within or on an outer surface of the windshield of the vehicle. For the antenna to effectively receive or transmit radio waves without interruption, it is also necessary to reduce surrounding electromagnetic interference with the antenna to the extent possible.
Although the clear films or coatings effectively reduce transmission of infrared radiation through the windshield, the clear films or coatings may also negatively impact the ability of the antenna to adequately transmit or receive radio waves. Specifically, as mentioned above, the clear films or coatings are electrically conductive and therefore naturally have the potential to interfere adversely with the radiation pattern and gain of the antenna on the windshield. Furthermore, where the clear films or coatings are applied over a substantial part of the windshield, there remains minimal space on the windshield to place the antenna such that the clear films or coatings do not adversely affect the functionality of the antenna.